A significant number of US high-school students regard their constitutional right to freedom of speech as excessive, according to a new survey.

Over a third of the 100,000 students questioned felt the First Amendment went "too far" in guaranteeing freedom of speech, press, worship and assembly.

Only half felt newspapers should be allowed to publish stories that did not have the government's approval.

The US government has committed itself to spreading "freedom" abroad.

In his second inaugural address, President George W Bush said the survival of liberty in the US depended on the success of liberty abroad.

Some rights groups have however attacked his administration for restricting civil liberties in measures that followed the 9/11 attacks on New York and Washington.

'Dangerous ignorance'

The two-year, $1m survey across US schools - in which 8,000 teachers were also interviewed - suggested students held a number of misconceptions about the First Amendment, and were more censorious on some issues than their elders.

Some 83% of students polled felt people should be allowed to express unpopular views, as opposed to 97% of teachers.

Roughly half the students polled wrongly believed the US government had the right to censor the internet, while two-thirds believed it was illegal to burn the US flag - another misconception.

The president of the John S and James L Knight Foundation, which conducted the research, said: "Ignorance about the basics of this free society is a danger to this nation's future."

The survey concluded that better teaching and a bigger emphasis on student journalism could raise awareness of the First Amendment in American classrooms.